1. Field of the Invention
This invention relates to vibrating feeders for receiving, storing and individually discharging workpieces, and to such a vibrating feeder, especially for feeding pins and/or springs to a tumbler lock pin setting machine.
2. Description of the Prior Art
A variety of vibrating feeding devices are known. A most common one of these includes a so-called vibrating pan feeder that is generally bowl-shaped with an inclinded ramp spiraling upwardly along the inside of the bowl from the bottom of the bowl to its upper edge. A supply of workpieces such as pins or springs is placed in the feeder which is then subjected to an asymmetrical circumferential vibration. That is to say, the bowl is vibrated circumferentially about its axis by alternating strong forward pulses and weaker return pulses. This vibration causes the workpieces to climb the ramp, one after the other, the ramp being lined with workpieces, so that they may be individually fed, for example, to a pin setting machine. However, this device suffers several disadvantages. Firstly, this type of device cannot uniformly orient the workpieces, as may be necessary when feeding workpieces having one end which differs from the other, such as a tumbler pin having one flat end surface and an opposing rounded end surface or "ball nose". Rather, the vibrating pan feeder can feed only workpieces with identical ends wherein orientation is unimportant. An additional disadvantage of the vibrating pan feeder is that a supply of springs placed in the feeder tend to become tangled with each other, inhibiting the orderly alignment and feeding of the springs end to end along the ramp.
Another type of feeder, various aspects of which are disclosed in German Pat. No. 348,367, U.S.S.R. Pat. No. 127,560, and Western Electric's Technical Digest No. 16 of October, 1969, includes a flat disc with an outwardly spiraling groove formed into the surface thereof. Workpieces are placed in a reservoir at the center of the disc and an asymmetric circumferential vibration applied to the disc causes the workpieces to spiral outwardly along the groove. While the grooves are a slight help for reducing tangling, the tangling and orientation disadvantages of the vibrating pan feeder are still present to a fair degree in this flat disc feeder. These advantages could be mitigated to some extent in the flat disc feeder if the workpieces were placed, preorientated, in the groove instead of being placed in the central reservoir. However, this represents a most inconvenient and expensive task. Further, without a central reservoir, the storage capability of this disc is directly related to its diameter and a large, bulky, and costly-to-machine disc would be needed to store operational quantities of pins or springs. Also, as the size of the disc increased, greater vibrational energies would have to be consumed to overcome the inertia of the disc.
An additional disadvantage common to both of these feeders is that the workpieces are supplied to the central portion of the feeder where the vibrating forces exerted thereon are the weakest.
It is believed that attempts have been made to store and feed workpieces through coiled tubes. It is believed that such attempts have been unsuccessful in that workpieces, such as pins or springs, have too little mass to be efficiently vibrated along the coiled tube without becoming fouled, i.e., jammed up. When fouling occurs, the production line must be shut down and the tubes cleared by forcing, for example, compressed air therethrough. Such fouling reduces production line productivity by increasing production line down time and by producing units that are deficient in parts and must be discarded.
These previous vibrating feeders have proved particularly unsuited to the complex and demanding task of feeding workpieces such as tumbler pins and springs to a tumbler lock pin setting machine.
In order to supply a steady flow of tumbler pins and springs to a tumbler lock pin setting machine such as those disclosed in U.S. Pat. Nos. 3,226,811; 3,274,673; and 3,417,452; a device is needed that can store, orientate and efficiently feed the tumbler springs and tumbler pins. The pins are made with pin making machines that are sometimes referred to as screw machines. These screw machines require substantial capital outlay, but have a pin production rate much greater than that demanded by a tumbler lock pin setting machine. Further, one screw machine can be quickly adjusted to produce the various lengths and shapes of pins that are used in the production of a tumbler lock. Thus, in just a fraction of a production day, a screw machine at its maximum output rate can produce all of the pins of any given size and shape required by the pin setting machine for that day. Consequently, a need arises for a feeding device that can store up to a day's supply of one type of pins, so that the screw machine can be efficiently used at its maximum output rate to produce all of the various sizes and shapes of pins required by the pin setting machine. As a pin setting machine can require ten pin styles and more, a substantial capital outlay savings is realized, in that only one, and not ten screw machines, is needed. Each style of pin can then be stored in its individual feeding device which need be replenished only once or twice during a production day. Also one feeding device can be used to store tumbler springs produced by a spring making machine at a rate many times greater than that required by the pin setting machine. In addition, the pin setting machine will require many asymmetrical pins, all fed properly oriented, end to end, to the machine. The machine will also require springs which obviously must be fed in an untangled state.
Hence, there exists a need, particularly for use with a tumbler lock pin setting machine, of a new and improved feeding mechanism capable of feeding workpieces such as pins and springs, oriented and untangled and which has a high storage capacity.